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21.
F.-R. Carminati M. Schiavoni L. Sanchez-Palencia F. Renzoni G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):249-254
We present a detailed experimental study of a three-dimensional lin⊥lin bright optical lattice. Measurements of the atomic
temperature and spatial diffusion coefficients are reported for different angles between the lattice beams, i.e. for different lattice constants. The experimental findings are interpreted with the help of numerical simulations. In particular
we show, both experimentally and theoretically, that the temperature is independent of the lattice constant.
Received 5 July 2001 and Received in final form 13 August 2001 相似文献
22.
P. E. Allegretti M. M. Schiavoni H. E. Di Loreto J. J. P. Furlong C. O. Della Vdova 《Journal of Molecular Structure》2001,560(1-3):327-335
The gas chromatographic behaviour for some β-ketoesters was studied. Additionally, the feasibility of the gas chromatographic separation of the corresponding tautomer forms was examined. In this work mass spectrometric detection allowed identification of both keto and enol forms and an estimation of their relative amounts for methylacetoacetate, -chloromethylacetoacetate, ethylacetoacetate and -chloroethylacetoacetate. This finding demonstrates slow tautomerisation kinetics permitting the chemical identity maintenance of the tautomers. 相似文献
23.
F.-R. Carminati M. Schiavoni Y. Todorov F. Renzoni G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):311-317
We describe the pump-probe spectroscopy of atoms cooled in a 3D lin⊥lin optical lattice. Our pump-probe configuration consists of two laser fields detuned with respect to the lattice fields.
This scheme allows to clearly identify in the probe transmission spectrum the Brillouin and Raman resonances, by studying
their positions as functions of the angle between the pump and probe beams. We describe these resonances in detail, and compare
the experimental results to the theoretical predictions. Our conclusions are supported by transport-spectroscopy measurements,
which allow to distinguish between contributions to the light scattering from propagating and non-propagating atoms.
Received 8 April 2002 / Received in final form 9 September 2002 Published online 12 November 2002 相似文献
24.
25.
We report a generalization of our earlier formalism [Pramana, 54, 663 (1998)] to obtain exact solutions of Einstein-Maxwell’s equations for static spheres filled with a charged fluid having
anisotropic pressure and of null conductivity. Defining new variables: w=(4π/3)(ρ+ε)r
2, u=4πξr
2, v
r=4πp
r
r
2, v
⊥=4πp
⊥
r
2[ρ, ξ(=−(1/2)F
14
F
14), p
r, p
⊥ being respectively the energy densities of matter and electrostatic fields, radial and transverse fluid pressures whereas
ε denotes the eigenvalue of the conformal Weyl tensor and interpreted as the energy density of the free gravitational field],
we have recast Einstein’s field equations into a form easy to integrate. Since the system is underdetermined we make the following
assumptions to solve the field equations (i) u=v
r=(a
2/2κ)r
n+2, v
⊥=k
1
v
r, w=k
2
v
r; a
2, n(>0), k
1, k
2 being constants with κ=((k
1+2)/3+k
2) and (ii) w+u=(b
2/2)r
n+2, u=v
r, v
⊥−v
r=k, with b and k as constants. In both cases the field equations are integrated completely. The first solution is regular in the metric as
well as physical variables for all values of n>0. Even though the second solution contains terms like k/r
2 since Q(0)=0 it is argued that the pressure anisotropy, caused by the electric flux near the centre, can be made to vanish reducing
it to the generalized Cooperstock-de la Cruz solution given in [14]. The interior solutions are shown to match with the exterior
Reissner-Nordstrom solution over a fixed boundary.
Dedicated to Prof. F A E Pirani. 相似文献
26.
The problem considered is the fitting of a many-body interaction potential to bulk crystal data. A parameterisation of the
potential is assumed which is based on physical considerations. The free parameters are determined by using global optimization
to perform a least squares fit, to a large number of crystal properties. This has been achieved for body centered cubic (bcc)
materials. The approach adopted here fits the bcc crystal structure, as the preferred minimum energy configuration for tungsten,
and also fits the dimer energetics and the elastic properties of crystalline tungsten. 相似文献
27.
The high optical transparency of ion plated indium oxide combined with their mechanical hardness and good environmental stability have opened up numerous applications in the line of sophisticated optoelectronic devices. Indium is evaporated at a low oxygen pressure on to an ordinary glass substrate mounted under the cathode and biased by a r.f. generator at 13,6 M Hz. Infrared spectra are recorded in the range 5000–200 cm?1 by A.T.R. and reflexion-absorption spectroscopy, and show between 800 and 200 cm?1 bands due to stretching and bending modes predicted by a factor group analysis. A tentative assignment is made of the highest frequency. Last U.V. and visible spectra are discussed. 相似文献
28.
29.
J. J. P. Furlong M. Mercedes Schiavoni E. A. Castro P. E. Allegretti 《Russian Journal of Organic Chemistry》2008,44(12):1725-1736
The review contains new data on tautomerism of organic compounds belonging to different classes, which were obtained by mass
spectrometry and confirmed by quantum-chemical calculations.
Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 12, pp. 1751–1763.
The text was submitted by the authors in English. 相似文献
30.
Carminati FR Sanchez-Palencia L Schiavoni M Renzoni F Grynberg G 《Physical review letters》2003,90(4):043901
We investigate Rayleigh scattering in dissipative optical lattices. In particular, following recent proposals [S. Guibal, Phys. Rev. Lett. 78, 4709 (1997)]; C. Jurczak, Phys. Rev. Lett. 77, 1727 (1996)]], we study whether the Rayleigh resonance originates from the diffraction on a density grating and is therefore a probe of transport of atoms in optical lattices. It turns out that this is not the case: the Rayleigh line is instead a measure of the cooling rate, while spatial diffusion contributes to the scattering spectrum with a much broader resonance. 相似文献